KR101333332B1 - Light emitting diode and method of manufacturing the same - Google Patents

Abstract

The light emitting diode according to the present invention comprises an n-type nitride semiconductor layer and a p-type nitride semiconductor layer and an active layer disposed therebetween, the first surface provided in an outward direction of the n-type nitride semiconductor layer, the p-type nitride semiconductor layer A light emitting stack having a second surface provided by the second surface opposite to the first surface and having a side inclined at an angle from the n-type nitride semiconductor layer to the p-type nitride semiconductor layer therebetween; A highly reflective metal portion formed on the second surface to be in contact with the p-type nitride semiconductor layer of the light emitting stack; An insulating structure formed to surround a side surface of the light emitting stack and a second surface on which the highly reflective metal part is formed; A p-side electrode portion connected to the highly reflective metal portion and exposed through the insulating structure portion; And an n-side electrode portion connected to the n-type nitride semiconductor layer of the light emitting stack portion to surround the outside of the insulating structure portion.

According to the light emitting diode according to the present invention and a method of manufacturing the same, a light emitting diode having a maximum light emitting area can be provided by removing a portion of the whole light emitting area that is covered by an electrode.

Light emitting diodes, luminous efficiency, electrode

Description

TECHNICAL FIELD The present invention relates to a light emitting diode (LED)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode and a method of manufacturing the same, and more particularly, to a light emitting diode having an improved electrode structure for improving light emitting efficiency and a method of manufacturing the same.

In general, a light emitting diode (LED) is a semiconductor device that emits light based on the recombination of electrons and holes, and is widely used as a light source in optical communication, electronic devices, and the like.

In the light emitting diode, the frequency (or wavelength) of light to be emitted is a band gap function of a material used in a semiconductor device. When a semiconductor material having a small band gap is used, photons with low energy and long wavelength are generated, When a semiconductor material having a band gap is used, short wavelength photons are generated.

For example, AlGaInP materials generate light at a red wavelength, and silicon carbide (SiC) and Group III nitride-based semiconductors, particularly GaN, emit blue or ultraviolet light.

Among them, since a gallium-based light emitting diode can not form a bulk monocrystalline GaN, a substrate suitable for growing GaN crystals should be used. Typically, a sapphire substrate is used.

1A and 1B are respectively a top view of a conventional LED having a flip-chip structure and an AA sectional view of the LED. FIG. 1A and FIG. 1B are views showing a conventional LED 20, for example, An active layer 23b and a p-type GaN clad layer 23c are sequentially formed on the active layer 23b and the p-type GaN clad layer 23c, An n-side electrode 26 and an un-etched p-type GaN clad layer 23c (not shown) are formed on the exposed n-type GaN clad layer 23a after exposing a part of the n-type GaN clad layer 23a by dry- The p-side electrode 25 is formed after the transparent electrode 24 is interposed.

Thereafter, microbumps 27 and 28 made of Au or Au alloy are formed on the p-side electrode 25 and the n-side electrode 26, respectively.

1B, the light emitting diode 20 mounts the micro bumpers 27 and 28 on a mount substrate or a lead frame through a bonding process.

In order to increase the luminous efficiency of such a conventional light emitting diode, the surface of the active layer is irregularly widened to increase the light emitting area or to reduce the electrode area to increase the light emitting area. However, it is difficult to process the light emitting diode with a certain limit.

In particular, since a portion of the conventional light emitting diode that is covered by the electrode occupies a substantial portion of the total light emitting area, many photons reflected or extinguished by the electrode are generated, which adversely affects the luminous efficiency substantially. There is a problem in that the size of the light emitting diode must be widened in order to generate efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode in which the light emitting area is increased to improve the light emitting efficiency by improving the electrode structure occupying a substantial part of the total light emitting area.

Another object of the present invention is to provide a method of manufacturing a light emitting diode in which the electrode structure is improved and the light emitting area is widened to improve the light emitting efficiency.

Embodiments of the present invention for achieving the above object includes an n-type nitride semiconductor layer and a p-type nitride semiconductor layer and an active layer disposed therebetween, and provided in an outward direction of the n-type nitride semiconductor layer. A first surface, a second surface provided by the p-type nitride semiconductor layer and positioned opposite to the first surface, and between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer at a predetermined angle therebetween; A light emitting stack having a photographic side surface; A highly reflective metal portion formed on the second surface to be in contact with the p-type nitride semiconductor layer of the light emitting stack; An insulating structure formed to surround a side surface of the light emitting stack and a second surface on which the highly reflective metal part is formed; A p-side electrode portion connected to the highly reflective metal portion and exposed through the insulating structure portion; And an n-side electrode portion connected to the n-type nitride semiconductor layer of the light emitting stack portion and surrounding the outside of the insulating structure portion.

In an embodiment of the present invention, the first surface of the light emitting stack is formed as an uneven surface in an outward direction.

In an embodiment of the present invention, the n-type nitride semiconductor layer includes a current diffusion layer connected to the n-side electrode part therein, and the current diffusion layer includes n-dopants three to 100 times more than the surrounding n-dopant content. It is characterized by containing.

In the embodiment of the present invention, the uneven surface is formed by an anisotropic etching method or an irregular growth method of Hemispherical grained (HSG) to grow the material of the n-type nitride semiconductor layer to grain.

In the embodiment of the present invention, the highly reflective metal part is characterized in that the layer made of any one metal selected from Ag, Al and Cr.

In the embodiment of the present invention, the insulating structure is characterized in that the material is made of silicon nitride, silicon oxide and polymer combined in the group consisting of, or SOG (Silicon On Glass).

In an embodiment of the present invention, the light emitting stack has a mesa structure by the first surface, the second surface, and side surfaces therebetween, and the predetermined angle at which the side slope is inclined is 0 ° based on the vertical direction. It is characterized by being inclined at an angle of <θ <90 °.

In addition, an embodiment of the present invention includes an n-type and p-type nitride semiconductor layer on a growth substrate and an active layer disposed therebetween, the first surface of the n-type nitride semiconductor layer in contact with the growth substrate, the first A light emitting stack having a second surface of the p-type nitride semiconductor layer located in a direction opposite to one surface and a side surface inclined at a predetermined angle from the n-type nitride semiconductor layer to the p-type nitride semiconductor layer therebetween. Forming a plurality; Forming each of the highly reflective metal parts connected to the second surface of the p-type nitride semiconductor layer; A plurality of p-side electrode portions surrounding the side surfaces of the light emitting stack portion and the second surface on which the highly reflective metal portion is formed and connected to the highly reflective metal portion and n-side electrode portions contacting the side surfaces of the n-type nitride semiconductor layer are formed. Forming an insulating structure having an exposed area; Filling a plurality of exposed regions formed in the insulating structure to form a p-side electrode portion and an n-side electrode portion; And removing the growth substrate and dicing the light emitting stacks separately.

In the embodiment of the present invention, the forming of the plurality of light emitting stacks may include sequentially forming an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the growth substrate; And etching the exposed upper surface of the growth substrate to form a plurality of spaced apart light emitting stacks having inclined sides from the p-type nitride semiconductor layer to the n-type nitride semiconductor layer. .

In the embodiment of the present invention, the growth substrate is characterized in that it is provided through lapping and polishing.

In the embodiment of the present invention, the dicing of the light emitting stacks may include forming a first surface of the n-type nitride semiconductor layer exposed by removing the growth substrate as an uneven surface. One side is characterized in that the irregular surface is formed by an anisotropic etching method or an irregular growth method of Hemispherical grained (HSG) to grow the grain of n-GaN.

In the embodiment of the present invention, the forming of the p-side electrode portion and the n-side electrode portion may be performed by filling an electrically conductive metal material with each of the exposed regions of the insulating structure by electrolytic or electroless plating to form an electrode layer covering the insulating structure. Making; And performing CMP (Chemical Mechanical Polishing) on the electrode layer so that the insulating structure is exposed.

In the embodiment of the present invention, the forming of the p-side electrode portion and the n-side electrode portion may include screen printing using a squeegee on a conductive paste including an electrically conductive metal material in each of the exposed regions of the insulating structure. Filling and curing the method to cover the insulating structure; And performing CMP on the conductive paste to expose the insulating structure.

As described above, in the present invention, the p-electrode and the n-electrode are formed on the surface opposite to the light emitting surface of the uneven surface, and the light emitting area is maximized by removing the portion of the entire light emitting area that is covered by the electrode. A light emitting diode can be provided.

The present invention also provides a light emitting diode having a mesa structure inclined from a p-GaN layer to an n-GaN layer, an n-electrode having an inclined surface, and a reflective film, thereby improving light reflectance to increase light emission efficiency. Can be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2A is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention, and FIG. 2B is a bottom view illustrating a bottom surface of the light emitting diode according to an embodiment of the present invention.

As shown in FIGS. 2A and 2B, the LED 100 according to the embodiment of the present invention includes an n-type nitride semiconductor layer 120 and a p-type nitride semiconductor layer 140 and an active layer disposed therebetween. 130, and provided by the n-type nitride semiconductor layer 120 and the p-type nitride semiconductor layer 140 and positioned in opposite directions to each other, with the first surface 121 and the second surface 141 interposed therebetween. The second surface 141 to be in contact with the p-type nitride semiconductor layer 140 having a side surface inclined at a predetermined angle from the type nitride semiconductor layer 120 to the p-type nitride semiconductor layer 140. Connected to the highly reflective metal part 150 formed on the upper surface of the light emitting stack and the second surface 141 on which the highly reflective metal part 150 is formed. P-type electrode portion 171 formed through exposure to insulating structure 160 and n-type nitride of light emitting stack And connected to the conductive layer 120 surrounding the outer side of the insulating structure 160 is configured to include an n-type electrode 172.

The light emitting stack includes an n-type nitride semiconductor layer 120, an active layer 130, and a p-type nitride semiconductor layer 140, and the n-type nitride semiconductor layer 120 is formed of, for example, n-GaN and is externally formed. And a current spreading layer 120-1 connected to the n-side electrode portion 172 therein, and the current spreading layer 120-1 has an n-dopant. Is formed to be 3 to 100 times more than the n-dopant content in the up and down direction, and the side surface of the light emitting stack is predetermined from the n-type nitride semiconductor layer 120 to the p-type nitride semiconductor layer 140 based on the vertical direction. It is formed to be inclined at an angle of, the light emitting laminated portion is formed as a mesa (mesa) or inverted rhombus structure by the first surface 121, the second surface 141 and the side surface therebetween as a whole.

In addition, the first surface 121 formed as a concave-convex surface outside the n-type nitride semiconductor layer 120 may be an anisotropic etching or an HSG for growing the material of the n-type nitride semiconductor layer 120 into grains as a light emitting surface. It is formed by the uneven surface on which a plurality of irregularities are formed by an irregular growth method such as (Hemispherical grained), and the side surface of the light emitting stacking portion has a predetermined angle (θ) with respect to the vertical direction, for example, 0 ° <θ <90 ° range. It may be formed at an angle of the inclined structure.

The active layer 130 has a predetermined band gap and is a layer in which quantum wells are made to recombine electrons and holes. For example, the active layer 130 may include InGaN, AlGaN, or AlGaN. Since the emission wavelength generated by the combination of electrons and holes is changed, it is preferable to adjust the material forming the active layer 130 according to the desired emission wavelength.

The highly reflective metal part 150 is a metal film made of a highly reflective metal material such as Ag, Al, Cr, etc. to reflect light, and is connected to the p-side electrode part 171 so that a voltage is applied thereto. It is possible to improve the luminous efficiency by reflecting the light generated from the 130 to be led to the first surface 121.

The insulating structure 160 is formed of an insulating material such as silicon nitride, silicon oxide, and a polymer combined to insulate the p-side electrode portion 171 and the n-side electrode portion 172. It is formed between the p-side electrode portion 171 and the n-side electrode portion 172 under the type nitride semiconductor layer 140 and the highly reflective metal portion 150, and is to be surrounded by the n-side electrode portion 172. Can be. Here, in the embodiment of the present invention, the insulating structure 160 is formed using SOG (Silicon On Glass).

The light emitting diode 100 according to the exemplary embodiment of the present invention configured as described above has a mesa or inverse rhombus structure in which side surfaces of the n-type nitride semiconductor layer 120 to the p-type nitride semiconductor layer 140 are inclined at a predetermined angle. The p-side electrode portion 171 and the n-side electrode portion 172 are disposed below, and the light generated from the active layer 130 is in contact with the highly reflective metal portion 150 or the side of the n-side electrode portion Since it is reflected from the inclined surface of 172 and scattered from the first surface 121 of the unevenness, the portion covering the entire light emitting area is removed by the electrode in the related art, thereby improving luminous efficiency.

Hereinafter, a method of manufacturing the LED 100 according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 3A to 3H.

3A to 3H are cross-sectional views illustrating a process of manufacturing a light emitting diode according to an embodiment of the present invention.

First, as shown in FIG. 3A, a method of manufacturing a light emitting diode 100 according to an embodiment of the present invention includes n having a current spreading layer 120-1 therein on a growth substrate 110. The type nitride semiconductor layer 120, the active layer 130, and the p-type nitride semiconductor layer 140 are formed.

The growth substrate 110 is a general substrate for manufacturing a light emitting diode, and for example, a material of any one of Al ₂ O ₃ , SiC, ZnO, Si, GaAs, GaP, LiAl ₂ O ₃ , BN, AIN, and GaN. The substrate may be made of, and may be provided through lapping and polishing to have a transparent and flat surface.

The n-type nitride semiconductor layer 120 having the current spreading layer 120-1 included therein on the substrate 110 includes 3 to 100 times more content of the n-dopant in the up and down direction. For example, the active layer 130 including, for example, AlGaN / AlGaN, is formed on the upper surface of the n-type nitride semiconductor layer 120 and the p-type nitride semiconductor layer 140 is formed, for example. And p-GaN layer doped with a p-type dopant such as magnesium (Mg). Here, in order to reduce lattice mismatch between the substrate 110 and subsequent layers during crystal growth of the n-type nitride semiconductor layer 120, the active layer 130, and the p-type nitride semiconductor layer 140, the substrate 110 and the n-type nitride A buffer layer (not shown) made of GaN, InN, or AlN may be formed between the semiconductor layers 120.

After the p-type nitride semiconductor layer 140 is formed on the substrate 110, the upper portion of the substrate 110 from the p-type nitride semiconductor layer 140 to the n-type nitride semiconductor layer 120 is illustrated in FIG. 3B. Anisotropic etching is performed to expose the surface to form a plurality of spaced apart light emitting stacks having a mesa or inverted rhombus structure having inclined sides from the p-type nitride semiconductor layer 140 to the n-type nitride semiconductor layer 120. do. Here, the angle θ that is inclined from the p-type nitride semiconductor layer 140 to the n-type nitride semiconductor layer 120 is adjusted to a predetermined angle θ based on the vertical direction by adjusting the process conditions of the anisotropic etching. For example, it may be etched at an angle in the range of 0 ° <θ <90 °.

After forming a plurality of light emitting stacks having inclined sides from the p-type nitride semiconductor layer 140 to the n-type nitride semiconductor layer 120, the upper portion of the p-type nitride semiconductor layer 140 as shown in FIG. 3C. On the surface, that is, the second surface 141, a highly reflective metal material such as, for example, Ag, Al, Cr, or the like is formed by using a physical vapor deposition (PVD) method, respectively.

Of course, the p-type nitride semiconductors of the p-type nitride semiconductor layers 140 to n-type nitride semiconductor layers 120 shown in FIG. 3a are not formed after the plurality of light emitting stacks are formed. After forming the highly reflective metal part 150 by region on the upper surface of the layer 140, anisotropic etching is performed to have an inclined side surface from the highly reflective metal part 150 to the n-type nitride semiconductor layer 120. The light emitting stack can also be formed.

After forming the highly reflective metal part 150, for example, silicon nitride, silicon oxide, and polymer may be used to insulate the p-side electrode part 171 and the n-side electrode part 172 as shown in FIG. 3D. Insulating structure 160 is formed of a material combined in the group consisting of.

Here, the insulating structure 160 is formed by forming a layer of a material formed from a group consisting of silicon nitride, silicon oxide, and polymer in the form of a layer by metal organic chemical vapor deposition (MOCVD) method to perform an etching process, as shown in Figure 3d As described above, the n-type includes the region exposing the surface of the highly reflective metal portion 150 to form the p-side electrode portion 171 and the current diffusion layer 120-1 to form the n-side electrode portion 172. The nitride semiconductor layer 120 may be formed to include an exposed area in the form of a closed curve that exposes to one side of the nitride semiconductor layer 120. In the embodiment of the present invention, the insulating structure 160 is formed using silicon on glass (SOG).

After forming the insulating structure 160 having a plurality of exposed regions for forming the p-side electrode portion 171 and the n-side electrode portion 172, the exposed region of the insulating structure 160 as shown in FIG. 3E. An electrode layer 170 covering each of the insulating structures 160 is formed by filling an electrically conductive metal material such as Au, Ni, Cu, or the like.

In this case, in order to form the electrode layer 170 covering the insulating structure 160 by filling the exposed area of the insulating structure 160, an electrically conductive metal material such as Au, Ni, Cu, or the like is filled by an electrolytic plating method or an electroless plating method. Alternatively, a conductive paste containing an electrically conductive metal material such as Au, Ni, Cu, or the like may be filled and cured by screen printing using a squeegee.

After the electrode layer 170 is formed, the substrate 110 is removed by performing a lift off or etching process using a laser as shown in FIG. 3F, and the substrate 110 as shown in FIG. 3G. A process for forming the uneven surface of the first surface 121 of the removed n-type nitride semiconductor layer 120 is performed.

Here, the process for forming the first surface 121 of the uneven surface is an anisotropic etching process or HSG (Hemispherical) to grow the material of the n-type nitride semiconductor layer 120 in the grain on the surface of the n-type nitride semiconductor layer 120 irregular growth method such as grained), and in the embodiment of the present invention, for example, the anisotropic wet etching is performed by performing anisotropic wet etching at a temperature of 80 ° C. for 20 minutes to 1 hour in an anisotropic wet etching process. The first surface 121 of can be formed.

After forming the first surface 121 of the uneven surface, as shown in FIG. 3H, CMP (Chemical Mechanical Polishing) is performed on the electrode layer 170 to expose the insulating structure 160, thereby forming the p-side electrode portion ( 171 and the n-side electrode portion 172 are formed.

After the p-side electrode portion 171 and the n-side electrode portion 172 are formed in this way, a dicing process is performed along the cutting line A shown in FIG. 3H to remove the uneven surface shown in FIG. 2A. The light emitting diodes 100 having one surface 121 are separated and completed.

Accordingly, the light emitting diode 100 according to the embodiment of the present invention forms the p-side electrode portion 171 and the n-side electrode portion 172 on a surface opposite to the first surface 121 of the uneven surface, and thus, has been conventionally known. The light-emitting area can be maximized by removing a portion of the entire light-emitting area that is covered by the electrode.

In addition, according to an embodiment of the present invention, the light emitting diode 100 has a mesa-structured light emitting stack having an inclined side surface from the p-type nitride semiconductor layer 140 to the n-type nitride semiconductor layer 120, and the n-type nitride semiconductor layer. An n-side electrode portion 172 having an inclined surface in contact with the 120 and a highly reflective metal portion 150 connected to the second surface 141 are formed to improve the reflectance of light to increase luminous efficiency. Can be.

Although the technical idea of the present invention has been specifically described according to the above preferred embodiments, it is to be noted that the above-described embodiments are intended to be illustrative and not restrictive.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

FIGS. 1A and 1B are a top view and a side sectional view of a conventional light emitting diode. FIG.

Figure 2a is a cross-sectional view showing the structure of a light emitting diode according to an embodiment of the present invention.

2B is a bottom view of a bottom surface of a light emitting diode according to an embodiment of the present invention;

3A to 3H are cross-sectional views illustrating a process of manufacturing a light emitting diode according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: light emitting diode 110: growth substrate

120: n-type nitride semiconductor layer 120-1: current diffusion layer

121: uneven surface 130: active layer

140: p-type nitride semiconductor layer 150: highly reflective metal portion

160: insulating structure portion 171: p-side electrode portion

172: n-side electrode portion

Claims (19)

an n-type nitride semiconductor layer and a p-type nitride semiconductor layer and an active layer positioned therebetween, provided by the first surface provided in the outward direction of the n-type nitride semiconductor layer, the p-type nitride semiconductor layer A light emitting stack having a second surface positioned opposite to the first surface and a side surface inclined at an angle from the n-type nitride semiconductor layer to the p-type nitride semiconductor layer therebetween; A highly reflective metal portion formed on the second surface to be in contact with the p-type nitride semiconductor layer of the light emitting stack; An insulating structure formed to surround a side surface of the light emitting stack and a second surface on which the highly reflective metal part is formed; A p-side electrode portion connected to the highly reflective metal portion and exposed through the insulating structure portion; And And an n-side electrode portion connected to the n-type nitride semiconductor layer of the light emitting stack portion to surround the outside of the insulating structure portion. The method of claim 1, The first surface of the light emitting laminated portion is formed as a concave-convex surface in the outward direction. The method of claim 1, The n-type nitride semiconductor layer includes a current diffusion layer connected to the n-side electrode portion therein, Wherein the current spreading layer contains n-dopant three to 100 times more than the surrounding n-dopant content. The method of claim 2, The uneven surface is formed by an anisotropic etching method or an irregular growth method of hemispherical grained (HSG) for growing the material of the n-type nitride semiconductor layer to grain. delete delete The method of claim 1, The insulating structure is a light emitting diode, characterized in that made of SOG (Silicon On Glass). The method of claim 1, The light emitting stack portion The mesa structure is formed by the first surface, the second surface and the side surfaces therebetween, And a predetermined angle at which the side surface is inclined is set at an angle in a range of 0 ° <θ <90 ° with respect to the vertical direction. A n-type and p-type nitride semiconductor layer on the substrate for growth and an active layer interposed therebetween, the first surface of the n-type nitride semiconductor layer in contact with the growth substrate, the first surface and the opposite side to the first surface Forming a plurality of light emitting stacks having a second surface of the p-type nitride semiconductor layer and a side surface inclined at an angle from the n-type nitride semiconductor layer to the p-type nitride semiconductor layer therebetween; Forming each of the highly reflective metal parts connected to the second surface of the p-type nitride semiconductor layer; A plurality of p-side electrode portions surrounding the side surfaces of the light emitting stack portion and the second surface on which the highly reflective metal portion is formed and connected to the highly reflective metal portion and n-side electrode portions contacting the side surfaces of the n-type nitride semiconductor layer are formed. Forming an insulating structure having an exposed area; Filling a plurality of exposed regions formed in the insulating structure to form a p-side electrode portion and an n-side electrode portion; And Removing the growth substrate and dicing the light emitting stacks separately Emitting diode. The method of claim 9, Forming a plurality of light emitting stacks Sequentially forming an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer on the growth substrate; And Etching to expose an upper surface of the growth substrate to form a plurality of light emitting stacks having a side surface inclined from the p-type nitride semiconductor layer to the n-type nitride semiconductor layer And forming a light emitting diode on the light emitting diode. delete delete delete delete delete delete delete The method of claim 9, Forming the p-side electrode portion and n-side electrode portion Forming an electrode layer covering each of the exposed regions of the insulating structure by filling an electrically conductive metal material with an electrolytic or electroless plating method; And Performing chemical mechanical polishing (CMP) on the electrode layer to expose the insulating structure; And forming a light emitting diode on the light emitting diode. The method of claim 9, Forming the p-side electrode portion and n-side electrode portion Filling and curing a conductive paste including an electrically conductive metal material in each exposed area of the insulating structure by a screen printing method using a squeegee to cover the insulating structure; And Performing CMP on the conductive paste to expose the insulating structure And forming a light emitting diode on the light emitting diode.

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